Chapter 8 Small Item Picking Systems

《 Main Knowledge 》 1. bin shelving systems 2. modular Storage Drawers/Cabinets 3. mezzanine 4. horizontal carousels 5. vertical carousels 6. automated item picking

Small Item Picking Systems The major types of broken case picking systems are picker-to-stock （PTS）system 拣选员移动式拣选系统 stock-to-picker （STP） system 存货移动式拣选系统 automated item picking 自动拣选系统

Small Item Picking Systems In picker-to-stock systems, the order picker walks or rides to the picking location. In stock-to-picker systems, the stock is mechanically transported to a stationary order picker. In automated item picking, items are automatically dispensed into shipping cartons or tote pans.

The two subsystems that 1. Picker-to-Stock Systems 拣选员移动式拣选系统 The two subsystems that must be selected are the storage system that houses the stock 货物存放系统 the item retrieval system 取货系统

The three most popular picker-to-stock storage systems are 1. Picker-to-Stock Systems 拣选员移动式拣选系统 The three most popular picker-to-stock storage systems are bin shelving 箱式货架 modular storage drawers 标准储存抽屉 gravity flow rack 重力式货架/自流式货架

1.1.1 Bin Shelving Systems Bin (or metal) shelving systems are the oldest and still the most popular equipment alternative for small parts order picking.

1.1.1 Bin Shelving Systems Advantages Disadvantages Inexpensive require very little if any maintenance Inflated labor requirement Supervisory problems Item security/protection problems Disadvantages

1.1.1 Bin Shelving Systems Disadvantages Space is frequently underutilized in bin shelving systems. Reasons are ◇ the full inside dimensions of a shelving unit are rarely usable. ◇ The height of bin shelving units may be limited by the reaching height of a human being. consequences are ◇ First, low space utilization means that a large amount of floor space is required to store the products. ◇ Second, the greater the floor space, the greater the area that must be traveled by the order pickers, and thus the greater the labor requirement and costs.

1.1.2 Modular storage drawers / cabinets Advantages 1. the large number of items that can be stored and presented to the order picker in a small area. 2. excellent storage density 3. because the drawers are pulled out into the aisle for picking, space does not have to be provided above each SKU to provide room for the order picker’s hand and forearm. 4. improved picking accuracy 5. protection for the items from the environment. Suitable for: When the value of space is at a true premium When facing the possibility of building additions Cost of space and the need for item security and protection are very high

1.1.3 Gravity Flow Rack Gravity flow rack is typically used for : SKUs with high broken case cube movements that are stored in fairly uniform sized and shaped cartons.

1.1.3 Gravity Flow Rack Advantages The back-to-front movement insures first-in-first-out （FIFO） turnover of the material. good space utilization. very low maintenance requirements Walking and therefore labor requirements can be reduced with an efficient layout. Advantages

1 1.1.4 Space Saving Systems Mezzanines The advantages of using a mezzanine is that nearly twice as much material can be stored in the original square footage. The major design issues for a mezzanine are the selection of the proper grade of mezzanine for the loading that will be experienced, the design of the material handling system to service the upper levels of the mezzanine, and the utilization of the available clear height.

1 1.1.4 Space Saving Systems Mezzanines The key to maintaining high-order picking productivity when a mezzanine is in use is to slot the products so that most of the picking activity takes place at the floor level.The SKUs with the highest picking density should be assigned to the floor level and the SKUs with the lowest picking density should be assigned to the upper level.

Mobile Storage Systems 1.1.4 Space Saving Systems 2 Mobile Storage Systems

Mobile Storage Systems 1.1.4 Space Saving Systems 2 Mobile Storage Systems space savings Advantage Disadvantage the increased time required to access the items. used for very slow-moving items and when space is very scarce and/or expensive.

1.2 Picker-to-stock retrieval methods 拣选员移动式取货方法 Cart Picking 手推车拣选 Tote （or Carton） Picking 拣货箱拣选 Man-up Systems 载人系统 Robotic Item Picking 机器人拣选

1 1.2 Picker-to-stock retrieval methods Cart Picking 手推车拣选 Batch picking carts are designed to enable an order picker to pick multiple orders on a picking tour, thus dramatically improving productivity as opposed to strict single-order picking for small order. Cart picking rates range from 70 to 120 lines per person- hour.

Tote (or Carton) Picking 1.2 Picker-to-stock retrieval methods Conveyors are used Order pickers may walk one or more totes through a single picking zone, partially completing several orders at a time, or an order picker may walk one or more totes through all picking zones, thus completing one or more orders on each pass through the picking zones. 2 Tote (or Carton) Picking 拣货箱拣选 Tote picking rates range from 150 to 300 lines per person hour.

3 1.2 Picker-to-stock retrieval methods Order picker truck; Man-up Systems 载人系统 Order picker truck; man-aboard AS/RS 载人自动存取系统 A man-aboard AS/RS offers significant floor space savings over the systems described so far. Advantage Man-aboard automated storage and retrieval systems are far and away the most expensive picker-to-stock equipment alternative. Disadvantage

3 4 1.2 Picker-to-stock retrieval methods Typical picking rates in man-aboard operations range between 40 and 250 lines per person-hour. 3 Man-up Systems 载人系统 Man-aboard systems are typically appropriate for slow-moving items where space is fairly expensive. 4 Robotic Item Picking 机器人拣选

The two most popular stock-to-picker storage systems are 2. STOCK-TO-PICKER SYSTEMS The two most popular stock-to-picker storage systems are Carousels 旋转式存储传送系统 Manila Automated Storage and Retrieval Systems 轻负载自动存取系统

2. STOCK-TO-PICKER SYSTEMS The major advantage of stock-to-picker systems over picker-to-stock systems The elimination of the travel time for the order picker supervision

2.1 Carousels 1 Horizontal carousels 水平旋转式存储传送系统 1 Horizontal carousels vary in length from 15 feet to 100 feet, and in height from 6 feet to 25 feet. The length and height of the units are dictated by the pick rate requirements and building restrictions.

2.1 Carousels 1 Horizontal carousels 水平旋转式存储传送系统 Drawback The throughput capacity is limited by the rotation speed of the motor drive. The initial investment of $40,000 to $70,000 per carousel unit. Drawback Items with a high cube movement should not be housed in carousels. Suitable for

2.1 Carousels 2 Vertical Carousels 垂直旋转式存储传送系统 Vertical carousels range in height from 8 feet to 35 feet. Heights are dictated by throughput requirements and building restrictions.

2.1 Carousels 2 Vertical Carousels 垂直旋转式存储传送系统 Advantages 1. Order pick times for vertical carousels are theoretically less than those for horizontal carousels 2. promotes more accurate picking 3. excellent item protection and security. The cost of a typical vertical carousel is around $100,000> Horizontal carousels

2.2 Miniload Automated Storage and Retrieval Systems Miniloads vary in height from 8 to 50 feet, and in length from 40 to 200 feet. As in the case with carousels, the height and length of the system are dictated by the throughput requirements. 2 1 2 1

2.2 Miniload Automated Storage and Retrieval Systems As the most sophisticated of the system alternatives described thus far, is should come as no surprise that the miniload carries the highest price tag of any of the order picking system alternatives. Another result of its sophistication is the significant engineering and design time that accompanies each system.Greater sophistication leads to greater maintenance requirements.

Typical picking accuracy is 99.97 percent. 3. Automated Item Dispensing Machines Typical picking rates are in the range of 1,500 to 2,000 picks per person-hour. Typical picking accuracy is 99.97 percent.

4. Broken case picking systems comparison and selection Summary Characteristics of Alternative Broken Case Picking Systems System Attribute Unit of Measure Bin Shelving Gravity Flow Racks Storage Drawers Horizontal Carousel Vertical Carousel Miniload AS/RS Automatic Dispersing Gross system cost Initial cost/ purchased Ft3 $5-15 $3-5 $25-30 $20-35 $40-70 $30-40 $300-600 per dispenset Net system cost Initial cost/ available Ft3 #10-30 $9-15 %31-38 $65-100 $38-50 Floorspace requirements Ft3 of inventory houses per Ft2 of floorspace 1-1.2 0.7-0.85 1.8-2.5 0.8-1.25 5.0-6.0 4.0-5.0 Human factors Ease of retrieval Average Good Excellent Maintenance requirements Low Medium High Item security Flexibility Ease to reconfigure Pick rate Order lines per person-hour C:25-125 T:100-350 M:25-250 W:300-500 50-250 50-300 25-125 500-1000 T=Tote picking C=Cart picking M=Man-aboard ASRS W=Wave picking